The vent for your vacuum system is a plastic pipe that just hangs about 2 inches in the cabin from the rubber grommet behind the brake booster.

Trace this out - if you smoke cigarettes you can pull a puff and blow in it and get someone to identify where its shooting out from.

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)